var util = {
    isBrowser: function isBrowser () {
        return process && process.browser
    },
    isNode: function isNode () {
        return !util.isBrowser()
    },
    uriEscape: function uriEscape (string) {
        var output = encodeURIComponent(string)
        output = output.replace(/[^A-Za-z0-9_.~\-%]+/g, escape)

        // AWS percent-encodes some extra non-standard characters in a URI
        output = output.replace(/[*]/g, function (ch) {
            return (
                '%' +
        ch
            .charCodeAt(0)
            .toString(16)
            .toUpperCase()
            )
        })

        return output
    },
    uriEscapePath: function uriEscapePath (string) {
        var parts = []
        util.arrayEach(string.split('/'), function (part) {
            parts.push(util.uriEscape(part))
        })
        return parts.join('/')
    },
    abort: {},
    each: function each (object, iterFunction) {
        for (var key in object) {
            if (Object.prototype.hasOwnProperty.call(object, key)) {
                var ret = iterFunction.call(this, key, object[key])
                if (ret === util.abort) break
            }
        }
    },

    arrayEach: function arrayEach (array, iterFunction) {
        for (var idx in array) {
            if (Object.prototype.hasOwnProperty.call(array, idx)) {
                var ret = iterFunction.call(this, array[idx], parseInt(idx, 10))
                if (ret === util.abort) break
            }
        }
    },
    arraySliceFn: function arraySliceFn (obj) {
        var fn = obj.slice || obj.webkitSlice || obj.mozSlice
        return typeof fn === 'function' ? fn : null
    },
    queryParamsToString: function queryParamsToString (params) {
        var items = []
        var escape = util.uriEscape
        var sortedKeys = Object.keys(params).sort()

        util.arrayEach(sortedKeys, function (name) {
            var value = params[name]
            var ename = escape(name)
            var result = ename + '='
            if (Array.isArray(value)) {
                var vals = []
                util.arrayEach(value, function (item) {
                    vals.push(escape(item))
                })
                result = ename + '=' + vals.sort().join('&' + ename + '=')
            } else if (value !== undefined && value !== null) {
                result = ename + '=' + escape(value)
            }
            items.push(result)
        })

        return items.join('&')
    },
    date: {
        getDate () {
            return new Date()
        },
        iso8601: function iso8601 (date) {
            if (date === undefined) {
                date = util.date.getDate()
            }
            return date.toISOString().replace(/\.\d{3}Z$/, 'Z')
        }
    },
    crypto: {
    /* eslint-disable no-use-before-define */
        crc32Table: [
            0x00000000,
            0x77073096,
            0xee0e612c,
            0x990951ba,
            0x076dc419,
            0x706af48f,
            0xe963a535,
            0x9e6495a3,
            0x0edb8832,
            0x79dcb8a4,
            0xe0d5e91e,
            0x97d2d988,
            0x09b64c2b,
            0x7eb17cbd,
            0xe7b82d07,
            0x90bf1d91,
            0x1db71064,
            0x6ab020f2,
            0xf3b97148,
            0x84be41de,
            0x1adad47d,
            0x6ddde4eb,
            0xf4d4b551,
            0x83d385c7,
            0x136c9856,
            0x646ba8c0,
            0xfd62f97a,
            0x8a65c9ec,
            0x14015c4f,
            0x63066cd9,
            0xfa0f3d63,
            0x8d080df5,
            0x3b6e20c8,
            0x4c69105e,
            0xd56041e4,
            0xa2677172,
            0x3c03e4d1,
            0x4b04d447,
            0xd20d85fd,
            0xa50ab56b,
            0x35b5a8fa,
            0x42b2986c,
            0xdbbbc9d6,
            0xacbcf940,
            0x32d86ce3,
            0x45df5c75,
            0xdcd60dcf,
            0xabd13d59,
            0x26d930ac,
            0x51de003a,
            0xc8d75180,
            0xbfd06116,
            0x21b4f4b5,
            0x56b3c423,
            0xcfba9599,
            0xb8bda50f,
            0x2802b89e,
            0x5f058808,
            0xc60cd9b2,
            0xb10be924,
            0x2f6f7c87,
            0x58684c11,
            0xc1611dab,
            0xb6662d3d,
            0x76dc4190,
            0x01db7106,
            0x98d220bc,
            0xefd5102a,
            0x71b18589,
            0x06b6b51f,
            0x9fbfe4a5,
            0xe8b8d433,
            0x7807c9a2,
            0x0f00f934,
            0x9609a88e,
            0xe10e9818,
            0x7f6a0dbb,
            0x086d3d2d,
            0x91646c97,
            0xe6635c01,
            0x6b6b51f4,
            0x1c6c6162,
            0x856530d8,
            0xf262004e,
            0x6c0695ed,
            0x1b01a57b,
            0x8208f4c1,
            0xf50fc457,
            0x65b0d9c6,
            0x12b7e950,
            0x8bbeb8ea,
            0xfcb9887c,
            0x62dd1ddf,
            0x15da2d49,
            0x8cd37cf3,
            0xfbd44c65,
            0x4db26158,
            0x3ab551ce,
            0xa3bc0074,
            0xd4bb30e2,
            0x4adfa541,
            0x3dd895d7,
            0xa4d1c46d,
            0xd3d6f4fb,
            0x4369e96a,
            0x346ed9fc,
            0xad678846,
            0xda60b8d0,
            0x44042d73,
            0x33031de5,
            0xaa0a4c5f,
            0xdd0d7cc9,
            0x5005713c,
            0x270241aa,
            0xbe0b1010,
            0xc90c2086,
            0x5768b525,
            0x206f85b3,
            0xb966d409,
            0xce61e49f,
            0x5edef90e,
            0x29d9c998,
            0xb0d09822,
            0xc7d7a8b4,
            0x59b33d17,
            0x2eb40d81,
            0xb7bd5c3b,
            0xc0ba6cad,
            0xedb88320,
            0x9abfb3b6,
            0x03b6e20c,
            0x74b1d29a,
            0xead54739,
            0x9dd277af,
            0x04db2615,
            0x73dc1683,
            0xe3630b12,
            0x94643b84,
            0x0d6d6a3e,
            0x7a6a5aa8,
            0xe40ecf0b,
            0x9309ff9d,
            0x0a00ae27,
            0x7d079eb1,
            0xf00f9344,
            0x8708a3d2,
            0x1e01f268,
            0x6906c2fe,
            0xf762575d,
            0x806567cb,
            0x196c3671,
            0x6e6b06e7,
            0xfed41b76,
            0x89d32be0,
            0x10da7a5a,
            0x67dd4acc,
            0xf9b9df6f,
            0x8ebeeff9,
            0x17b7be43,
            0x60b08ed5,
            0xd6d6a3e8,
            0xa1d1937e,
            0x38d8c2c4,
            0x4fdff252,
            0xd1bb67f1,
            0xa6bc5767,
            0x3fb506dd,
            0x48b2364b,
            0xd80d2bda,
            0xaf0a1b4c,
            0x36034af6,
            0x41047a60,
            0xdf60efc3,
            0xa867df55,
            0x316e8eef,
            0x4669be79,
            0xcb61b38c,
            0xbc66831a,
            0x256fd2a0,
            0x5268e236,
            0xcc0c7795,
            0xbb0b4703,
            0x220216b9,
            0x5505262f,
            0xc5ba3bbe,
            0xb2bd0b28,
            0x2bb45a92,
            0x5cb36a04,
            0xc2d7ffa7,
            0xb5d0cf31,
            0x2cd99e8b,
            0x5bdeae1d,
            0x9b64c2b0,
            0xec63f226,
            0x756aa39c,
            0x026d930a,
            0x9c0906a9,
            0xeb0e363f,
            0x72076785,
            0x05005713,
            0x95bf4a82,
            0xe2b87a14,
            0x7bb12bae,
            0x0cb61b38,
            0x92d28e9b,
            0xe5d5be0d,
            0x7cdcefb7,
            0x0bdbdf21,
            0x86d3d2d4,
            0xf1d4e242,
            0x68ddb3f8,
            0x1fda836e,
            0x81be16cd,
            0xf6b9265b,
            0x6fb077e1,
            0x18b74777,
            0x88085ae6,
            0xff0f6a70,
            0x66063bca,
            0x11010b5c,
            0x8f659eff,
            0xf862ae69,
            0x616bffd3,
            0x166ccf45,
            0xa00ae278,
            0xd70dd2ee,
            0x4e048354,
            0x3903b3c2,
            0xa7672661,
            0xd06016f7,
            0x4969474d,
            0x3e6e77db,
            0xaed16a4a,
            0xd9d65adc,
            0x40df0b66,
            0x37d83bf0,
            0xa9bcae53,
            0xdebb9ec5,
            0x47b2cf7f,
            0x30b5ffe9,
            0xbdbdf21c,
            0xcabac28a,
            0x53b39330,
            0x24b4a3a6,
            0xbad03605,
            0xcdd70693,
            0x54de5729,
            0x23d967bf,
            0xb3667a2e,
            0xc4614ab8,
            0x5d681b02,
            0x2a6f2b94,
            0xb40bbe37,
            0xc30c8ea1,
            0x5a05df1b,
            0x2d02ef8d
        ],
        /* eslint-disable no-use-before-define */

        crc32: function crc32 (data) {
            var tbl = util.crypto.crc32Table
            var crc = 0 ^ -1

            if (typeof data === 'string') {
                data = new util.Buffer(data)
            }

            for (var i = 0; i < data.length; i++) {
                var code = data.readUInt8(i)
                crc = (crc >>> 8) ^ tbl[(crc ^ code) & 0xff]
            }
            return (crc ^ -1) >>> 0
        },

        hmac: function hmac (key, string, digest, fn) {
            if (!digest) digest = 'binary'
            if (digest === 'buffer') {
                digest = undefined
            }
            if (!fn) fn = 'sha256'
            if (typeof string === 'string') string = new util.Buffer(string)
            return util.crypto.lib
                .createHmac(fn, key)
                .update(string)
                .digest(digest)
        },

        md5: function md5 (data, digest, callback) {
            return util.crypto.hash('md5', data, digest, callback)
        },

        sha256: function sha256 (data, digest, callback) {
            return util.crypto.hash('sha256', data, digest, callback)
        },

        hash: function (algorithm, data, digest, callback) {
            var hash = util.crypto.createHash(algorithm)
            if (!digest) {
                digest = 'binary'
            }
            if (digest === 'buffer') {
                digest = undefined
            }
            if (typeof data === 'string') data = new util.Buffer(data)
            var sliceFn = util.arraySliceFn(data)
            var isBuffer = util.Buffer.isBuffer(data)
            // Identifying objects with an ArrayBuffer as buffers
            if (
                util.isBrowser() &&
        typeof ArrayBuffer !== 'undefined' &&
        data &&
        data.buffer instanceof ArrayBuffer
            ) {
                isBuffer = true
            }

            if (
                callback &&
        typeof data === 'object' &&
        typeof data.on === 'function' &&
        !isBuffer
            ) {
                data.on('data', function (chunk) {
                    hash.update(chunk)
                })
                data.on('error', function (err) {
                    callback(err)
                })
                data.on('end', function () {
                    callback(null, hash.digest(digest))
                })
            } else if (
                callback &&
        sliceFn &&
        !isBuffer &&
        typeof FileReader !== 'undefined'
            ) {
                // this might be a File/Blob
                var index = 0
                var size = 1024 * 512
                var reader = new FileReader()
                reader.onerror = function () {
                    callback(new Error('Failed to read data.'))
                }
                reader.onload = function () {
                    var buf = new util.Buffer(new Uint8Array(reader.result))
                    hash.update(buf)
                    index += buf.length
                    reader._continueReading()
                }
                reader._continueReading = function () {
                    if (index >= data.size) {
                        callback(null, hash.digest(digest))
                        return
                    }

                    var back = index + size
                    if (back > data.size) back = data.size
                    reader.readAsArrayBuffer(sliceFn.call(data, index, back))
                }

                reader._continueReading()
            } else {
                if (util.isBrowser() && typeof data === 'object' && !isBuffer) {
                    data = new util.Buffer(new Uint8Array(data))
                }
                var out = hash.update(data).digest(digest)
                if (callback) callback(null, out)
                return out
            }
        },

        toHex: function toHex (data) {
            var out = []
            for (var i = 0; i < data.length; i++) {
                out.push(('0' + data.charCodeAt(i).toString(16)).substr(-2, 2))
            }
            return out.join('')
        },

        createHash: function createHash (algorithm) {
            return util.crypto.lib.createHash(algorithm)
        }
    }
}



util.crypto.lib = require('crypto')
util.Buffer = require('buffer').Buffer
util.url = require('url')
util.querystring = require('querystring')
module.exports = util
